The present disclosure relates to a display unit displaying an image, a display method used for such a display unit, and an electronic unit including such a display unit.
In recent years, display units are incorporated into various electronic systems. Various kinds of display units such as liquid crystal display units, plasma display units, and organic EL display units have been developed in terms of image quality, power consumption, and the like, and display units are applied to various electronic systems including not only stationary televisions, but also cellular phones and portable information terminals according to characteristics of the display units.
A typical display unit includes a memory generally called frame memory. The frame memory temporarily holds one frame of an image signal supplied from an external host of the display unit. Therefore, the display unit performs a display operation at a timing determined by the display unit independently of the image signal, based on the image signal supplied from the external host of the display unit at a timing determined by the host.
In recent years, attention has been given to a display including a contact detection device, i.e., a so-called touch panel mounted on or integrated with a display panel, and displaying various button images and the like on the display panel, thereby allowing a user to input information with use of the button images instead of typical mechanical buttons. As an input device such as a keyboard, a mouse, or a keypad is not necessary for a display including such a touch panel, there is a tendency to expand the use of such a display into not only computers but also portable information terminals such as cellular phones.
There are some kinds of touch panels such as optical touch panels, resistive touch panels, and capacitive touch panels. For example, Japanese Unexamined Patent Application Publication No. 2009-258182 proposes a so-called in-cell type touch detection function-equipped display unit, in which a capacitive touch panel uses a common electrode for display intrinsically included in a display panel as one of a pair of electrodes for a touch sensor, and the other electrode (a touch detection electrode) is disposed to intersect with the common electrode. In the touch detection function-equipped display unit, an AC drive signal reversing its polarity every horizontal period of a display operation is applied to the common electrode to be transmitted to the touch detection electrode through a capacitance between the common electrode and the touch detection electrode. Then, a touch is detected based on a detection signal supplied from the touch detection electrode.